Process and apparatus for treating



June 27, 1939. A, WALLACH 2,163,642

PROCESS AND APPARATUS FOR TREATING SHEET MATERIAL Filed May 21, 1936INVENTOR ATTORNEYS Patented June 27, 1939 PATENT or-Fics PROESS ANDAPPARATUS FOR TREATING SHEET MATERIAL Andr Wallach, Atlanta, Ga.,asslgnor a Sylvania Industrial Corporatio I n, Frederlcksburg, Va., acorporation of Virginia Application May 21, 1938, Serial, No. 81,054

14 Claims.

The invention relates to a method and apparatus for modifying thesurface characteristics of stacked sheets of non-fibrous, relativelyplastic materials and the article produced thereby.

Wrapping materials formed from non-fibrous,

relatively plastic materials such as cellulose hydrate, cellulosederivatives, gelatin and synthetic resins are characterized by a highsurface gloss, ahigh degree of transparency, a smooth surface and arelative expansibility. Sheets of such materials tend to stick togetherwhen tightly rolled or stacked, especially when stored under pressure orin atmosphere which varies with respect to temperature and humidity. Thetackiness of such p'lasticized sheet materials is dependent, among otherfactors, upon (1) the thickness of the sheets, (2) the nature and amountof the plasticizer and (3) the temperature and relative humidity of theambient atmosm phere. Under the same atmospheric conditions, a thicksheet can tolerate a larger percentage of plasticizer than a thin sheet.Thus with sheets of cellulose hydrate varying in thickness of fromapproximately 0.0008 to 0.0016 of an inch, the

about 11% to 19% by weight.

The amount of plasticizer is varied with the seasons of the year.Cellulose hydrate sheets plasticized with 12% glycerine will exhibit noobjectionable tackiness on a moderate day in spring, while these sheetswill stick together on a vhumidday in summer and will be brittle on acold and dry day in winter or fall. As the temperature and relativehumidity increase, the tackiness of the sheets also increases. 7

The above mentioned factors taken together with the smoothness of thesheet materials give rise to numerous dimculties in the. use of thematerials. For example, when such material is cut into sheets and thesheets stacked, it frequently happens that the contiguous surfaces sticktogether to such an extent that it is difficult to separate theindividual sheets from the stack. Occasionally after prolonged storage,particularly when under pressure, the sheets stick together to such anextent that. the stack may become substantially a unitary block of thematerial so that this action is commonly referred to in the trade as"blocking. The sticking together of the 5 sheets greatly decreases thespeed of manipulating such materials in manual wrapping and renders itsubstantially impossible to use such sheets in automatic machinesresulting in inconvenience, waste and expense.

It is a general object of the invention to preglycerine content variescorrespondingly from a process and apparatus for treating stacked 15sheets of non-fibrous, flexible materials whereby to decrease thetendency of contiguous surfaces of the sheets to stick together and todecrease the tackines's of the surfaces thereof to facilitate the use ofthe sheets in manual operations and in automatic machinery.

It is another object of the invention to provide a process and apparatusfor reconditioning stacked sheets of non-fibrous materialssimultaneously to improve their flexibility and to de- 5 crease thetendency of the sheets to stick together.

It is a further specific object of the invention to provide a stack ofsheets of non-fibrous materials, the sheets being provided with means tofacilitate their individual separation from the stack.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has now been found that stacked sheets of flexible non-fibrousmaterials may be rendered in- 35 sensitive (in a blocking" sense) tovariations in plasticizer, humidity, temperature and storage conditionsgenerally by inserting between contiguous surfaces of the stacked sheetsa small amount of a comminuted material. In the now preferred embodimentof the invention, the edges of the sheets in a face of a stack, eitherbefore or after they have become stuck together, are subjected to ablast of the gas containing a comminuted materiaL' If the sheets are toobrittle, the stack may be subjected simultaneously or separately to agas consisting of or comprising a softening agent of the sheet material.Generally speaking, the apparatus of the invention consists of means toproduce a current of a gas, such as air, means to disperse in the gascurrent a comminuted material and means to position a stack of sheetsedgewise in the gas current. i

- The invention accordingly comprises a process having the several stepsand the relation of one and other non-fibrous sheet materials.

or more of such steps with respect to each of the others, the apparatusembodying features of construction, combinations and arrangement ofparts adapted to effect such steps, and the article which 7 possessesthe characteristics, properties and relation of elements, all asexemplified in the detailed disclosure hereinafter set forth and thescope of the invention will-be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing, in which:

Fig. 1 is a. perspective view of one embodiment of the apparatus of theinvention; 5

, Fig. 2 is anenlarged sectional view taken on line 22 of Fig. 1;

Fig. 3 is a detailed view in section with parts broken away of a sideelevation of a part of the apparatus of Fig. 1;

Fig. 4 is an enlarged sectional view with parts broken away of a secondembodiment of a part of the apparatus which is illustrated in Fig. 3;and

Fig. 5 is an embodiment of the stack-holding means of the apparatus ofFig. 1.

The process and apparatus are applicable for treating stacked sheets ofvarious non-fibrous materials, in particulancolloidal materials swellingin water such, for example, as cellulose hydrate, hydroxy-alkylderivatives of cellulose, gelatin, casein and'the like; as well ascellulose derivatives such, for example,'as cellulose acetate, cellulosenitrate, methyl cellulose and benzyl cellulose; also rubber andsynthetic resins such, for example, as polymerized vinyl resins,glyptal"'resins It is to be understood that such sheet materials may ormay not contain suitable plasticizers, fillers, and may or may not becoated and/or impregnated with waterproofing and moistureprooflngcompositions. I

For the comminuted material there may be employed an inorganic ororganic solid, preferably one which is cheap, non-hygroscopic andrelatively soft so as not to scratch the surface of the sheet materials,the parts of automatic machinery in which the treated sheets may beused,

or articles wrapped therein. Suitable comminutedv materials areinorganic substances such as barium sulphate, zinc oxide, talc, fullersearth or organic substances such as flour, starch, dextrine, anthracene,alkali metal earth soaps, as well as comminuted material of likecharacter to the sheet material such as cellulose hydrate, cellulosederivatives, gelatin, casein and the like. In the now preferredembodiment of the process,

- starch is employed since this material is cheap,

relatively soft and non-gritty.

While there is a wide range permissible in the size of the particles ofthe comminuted material, it has been found preferable, in order toobtain the correlated results herein described without interfering withthe generally accepted uses and properties of the sheet material, toemploy material in the form of a powder, the particles oi,

which are not substantially greater than those which will pass through a100 mesh screen and may have a size corresponding to 200 mesh or more.The comminuted material is applied uniformly over the surfaces of thesheet material in a very small amount, preferably in an ampuntinsufllcient materially to detract from the normal appearance of thesheet material.

Referring to the drawing, Fig. 1 is a perspective view of one embodimentof an apparatus suitable for carrying out the process, in which acurrent oi a gas may be supplied from a cylinder in having a valve II,the gas flowing through a conduit I2 having a pressure gauge H to amanifold I4 and to a plurality of outlet nozzles Iii-l5. The comminutedmaterial It contained in a vessell'l is sucked into the pipe i2 adjacentthe manifold II or directly into the manifold through a pipe It, thebottom end of which dips into the comminuted material. The stack is ofsheets is supported upon a bed plate 20, preferably pivotally supportedupon a stand 2!. The bed. plate is provided with a fixed back plate 22and end plates 23 and 24. The end plate 23 is provided with conventionalmeans to adjust its distance from the'plate 24. A top plate 25 ispreferably supported on the end plate 24 by conventional means (notshown) for adjusting its height from the bed plate whereby toaccommodate stacks of diflerent heights therebetween. The wall of theend plate 24 is provided with a plurality of slit-like openings -46corresponding in spacing and size to the several nozzles lfi-IE. The bedplate 20, being pivotally mounted on the stand 28, is provided withmeans such as a rod 2'! sliding in a sleeve 28 to vary the inclinationthereof. To allow the bed plate to be pivotally moved the pipe i8 shouldbe termed of flexible hosing or have a flexible section therein and thepipe I! should be provided with a suitable union or flexible section.

In carrying out the process, a stack l9 of sheets is placed on the bedplate 20 flush against the back plate 22 and end plate 24. The end plate23 is then moved toward the plate 24 until the edges of thesheets in aface of the stack are firmly pressed thereagainst. If the sheets in thestack are firmly stuck together or blocked, it is preferable first toknead or flex the stack across the straight edge 29 of the bed plate 20so as to loosen up the-stack.

To carry out the process with the apparatus of Fig. 1 the valve II isopened and the gas current causes the comminuted material I 6 in thevessel H to be sucked through the pipe I 8 and into the manifold M whereit isdispersed in the gas. The gas containing the dispersed comminutedmaterial passes from the nozzles I5i5 through the openings Eli-26against the edge 30 of the stack is of sheets, as shown in Fig. 3. Theforce of the current of gas causes the individual sheets 3! of the stackit to separate and the gas passing between the sheets deposits theparticles 32 of the comminuted material on the surfaces of the sheets.

There is shown in Fig. 4 an embodiment of the apparatus of Fig. 1 inwhich there are provided means for forcing the stack E9 to assume theshape of a trapezoid so as to produce a progressive overlapping orofiset of the successive sheets at the end as shown. For example, theend plates 23 and 25 are inclined at an angle, preferably less than 90,with respect to the bed plate 20 so that the edge 30 of the stack whichis positioned in the current of gas is overhanging as shown in Fig. 4.As a result of this novel arrangement, the entrance of the gas betweenthe contiguous sheets is facilitated.

Another method of facilitating the separation of the sheets is toprovide means to flex or corrugate the stack. For example, the bed plate2| and the top plate 25 may be provided with alternating ribs 33 whichfunction to flex the sheets one or more times, or corrugate the stack asshown in Fig. 5. when the stack is thus flexed or corrugated, air spaces34- are formed between adjacent sheets at intervals in the stack wherethe sheet changes direction intermediate of opposing ribs as shown inthe drawing.

If the stacked sheet material is found to be dried out and brittle, thegas used for separating the sheets may advantageously consist of orcomprise a known softening agent of the material and such trgitmentmaybe made simultaneously with or subsequent to the treatment with thecomminuted material. For example, a suitable water aspirator is attachedto the gas line I! and there is formed in the manifold ll a mixture ofair, water vapor and comminuted material of nomhygroscopic character.This mixture is suitable for separating and simultaneously resofteningbrittle sheets of regenerated cellulose. On the other hand, a mixture ofair and alcohol vapor may be used with suitable comminuted material forseparating and softening sheets of cellulose acetate.

For the compressed gas cylinder l0 there may be substituted an aircompressor with a suitable motor to operate the same in a known manner.The gas pressure required to provide a suitable current will vary withthe sheet material and the condition of the stack at the time oftreatment. In the appended claims, the expression gas current" isintended to cover a current of sufllcient volume and force to cause aseparation of the sheets in the stack being treated.

The stack may be slightly inclined from the horizontal or positionedsubstantially vertically in the supporting means and the lower edges ofthe sheets subjected to the blast of gas containing comminuted materialby a suitable appara tus embodying the features of the invention. Whendisposed in this manner, the effect of gravity is partly overcome andthe separation of the sheets facilitated. To further facilitate theseparation of the sheets, the end plate 2| may be out out at a pointintermediate its ends so that the edges of the sheets in the stack maybe riilled by hand while the gas current is played against the edges ofthe sheets. If desired, the end plate 23 may be suitably perforated toallow ready passage of the gas through the stack or the openings 26-26may be placed in the back plate 22, particularly when the stack is to bepositioned substantially vertically.

The product resulting from the novel process of the invention is notmaterially altered in its general appearance. When a transparentmaterial is treated with particles of a size corresponding to 100 meshor above, the deposit of comminuted material is practically invisible,the transparency and lustre of the sheet being substantially unimpaired.The sheets in the treated stack are free-flowing and may be separatedeasily by hand or automatic devices.

It appears probable that the various novel characteristics exhibited bythe treated material may be ascribed in part to the presence of theparticles anchored on the surface, and in part to the pockets of airprovided by them, which latter decrease the adherence by preventing thedirect contact of large smooth surface areas;

Since certain changes may be made in carrying out the above process andin the article, and modifications effected in the apparatus forpracticing the principle thereof, without departing from the scope ofthe invention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting 1 sense.

I claim:

1. A process for treating a stack of sheet materials to render theindividual sheets separable comprising depositing from a gaseousdispersion and between contiguous surfaces of the sheets while in saidstack a small amount of comminuted solid material.

2. A process for treating a stack of sheet materials to render theindividual sheets separable comprising inserting between contiguoussurfaces of the sheets while stacked a thin layer of gas carrying asmall amount of comminuted solid material.

3. A process for treating a stack of sheet materials to render theindividual sheets separable comprising positioning a stack of sheetsedgewise in a current of a gas containing a comminuted solid material todeposit between contiguous surfaces of the sheets a small amount of saidcomminuted material.

4. A process for treating a stack of "sheet materials to' render, theindividual sheets separable comprising subjecting edges of sheets in aface of a stack to a current of a gas containing comminuted solidmaterial to deposit between contiguoussurfaces of the sheets a smallamount of said comminuted material.

5. A process for treating a stack of sheet materials to render theindividual sheets separable comprising separating the individual sheetsof astack of sheets by means of a blast or air, and blowing in anddepositing between the contiguous surfaces of the sheets a small amountof comminuted solid material.

6. A process for treating a stack of sheet materials to render theindividual sheets separable comprising blowing in and depositing betweencontiguous surfaces of the sheets while in said stack a multiplicity ofparticles of comminuted solid material .in an amount insuflicient todetract substantially from the normal appearance of the individualsheets.

7. A process for treating a stack of sheet materials to render theindividual sheets separable comprising flexing the stack of sheets andpositioning the stack of sheets edgewise in a current of a gascontaining comminuted solid material to deposit between contiguoussurfaces of the sheets a small amount of said comminuted material.

8. A process for treating a stack of sheet materials to render theindividual sheets separable comprising kneading the stack of sheetsuntil the edges of the sheets are slightly out of line at one face ofthe stack and subjecting the edges of the sheets in said face to acurrent of gas containing a small amount of comminuted solid material todeposit between contiguous surfaces of the sheets a small amount of saidcomminuted material.

I 9. A process for treating a stack of sheet materials to render theindividual sheets separable comprising flexing the stack to separate theedges of the sheets in a face of the stack in at least one place andsubjecting said face at said place to a current of gas containingcomminuted solid material to deposit between contiguous surfaces of thesheets a small amount of said comminuted material.

10. A process for treating a stack of sheet materials to render theindividual sheets separable comprising corrugating the stack andsubjecting the edges of the sheets in a face of the stack which istransverse said corrugations to a current of a gas containing comminutedsolid material to deposit between contiguous surfaces of the sheets asmall amount of said comminuted material.-

11. A process for treating a stack of sheet materials to render theindividual sheets separable comprising subjecting edges of sheets in aface of a stack to a current of a gas containing comminuted solidmaterial to deposit between contiguous surfaces of the sheets a smallamount of said comminuted material and riilling the edges exposed to thecurrent.

12. A process for treating a stack of sheet materials to render theindividual sheets separable comprising disposing the stack on anedgeface and subjecting the lower edges of the sheets to a. current of agas containing comminuted solid material. to deposit between contiguoussurfaces of the sheets a small amount of said comminuted material.

13. As an article of manufacture. a stack of massage flexible sheets ofplasticized non-fibrous material and particles of a comminuted solidmaterial distributed between the individual sheets to render the sheetsreadily separable from each other, the comminuted material being of suchparticle size 5 and present in such an amount as not to detractsubstantially from the normal appearance of the sheet material.

14. As an article of manufacture, a stack of flexible sheets ofplasticized non-fibrous material from the normal appearance of the sheetmaterial.

' ANDRE WALLACE.

